version 13 attached. On Tue, Jan 28, 2025 at 1:49 PM Robert Treat <r...@xzilla.net> wrote: > > On Mon, Jan 27, 2025 at 12:45 PM Melanie Plageman > <melanieplage...@gmail.com> wrote: > > > > On Fri, Jan 24, 2025 at 3:43 PM Robert Haas <robertmh...@gmail.com> wrote: > > > > > > On Fri, Jan 24, 2025 at 3:02 PM Melanie Plageman > > > <melanieplage...@gmail.com> wrote: > > attached v11 uses a fraction with this name. It follows the > > conventions and I find it descriptive. > > > > Changing the configuration to a fraction does mean that quite a few of > > the comments are different in this version. I think the description of > > the guc in > > config.sgml could use some review in particular. I tried to make it > > clear that the percentage is not the maximum number of blocks that > > could be eager scanned, because you may also eagerly scan blocks and > > succeed. > > > > Specifies the maximum fraction of pages that <command>VACUUM</command> > may scan and <emphasis>fail</emphasis> to set all-frozen in the > visibility map before disabling eager scanning. A value of 0 disables > eager scanning altogether. The default is 0.03 (3%). > > Note that when eager scanning is enabled, successful page freeze > attempts will not count against this limit, although they are > internally capped at 20% of the all-visible but not all-frozen pages > within the relation, in an effort to amortize overhead for future > aggressive vacuums. > > This parameter can only be set in the > <filename>postgresql.conf</filename> file or on the server command > line; but the setting can be overridden for individual tables by > changing the <link > linkend="reloption-vacuum-max-eager-freeze-failure-rate">corresponding > table storage parameter</link>. For more information, see <xref > linkend="vacuum-for-wraparound"/>.
Thanks! I've updated it to mostly be the same as your suggestion. > > Other note: I noticed AutoVacOpts that are floating point numbers (like > > vacuum_cost_delay) are float8s but their associated GUCs (like > > autovacuum_vacuum_cost_delay) are doubles. These are going to be equivalent, > > but I wanted to note the inconsistency in case I was missing something. > > > > ::thinking emoji:: > > I think what you have is right, though certainly better to have a more > qualified opinion. > On a not entirely related item, I find it interesting that you set > your max value to 1.0, but vacuum_scale_factor (and similar) set to > 100.00. > I think you have it right though, what does it mean to set a table's > scale factor to 10,000%? Yes, I was a bit torn about this. The other GUCs with "rate" or "fraction" in the name -- log_transaction_sample_rate, log_statement_sample_rate, cursor_tuple_fraction, etc have a min of 0 and a max of 1 -- and their docs mention they are a "fraction of X". However, the gucs with "factor" in the name -- e.g. autovacuum_vacuum_scale_factor have a min of 0 and a max of 100 -- but those are taken as fractions. So, if you specify 50, that isn't 50% but 5000% (which is what you are saying). AFAICT, that just gets multiplied by reltuples and added to the base threshold in relation_needs_vacanalyze(). So, I mean I guess maybe that is purposeful, but it is quite confusing. I imagine there are some users out there with it set to 20 thinking that means 20% of reltuples when it really means 20x reltuples. > > I have changed it to DEBUG2. I started it as INFO because the other vacuum > > messages about whether or not the vacuum is an aggressive vacuum were at > > INFO > > level.I don't know what a user might prefer. Treat said this downthread: snip > > I'm happy to go either way. I don't want users mad about verbosity, but if > > they > > think it's helpful, then that seems good. > > If there is a configurable, people will want to tune it, and DEBUG > level messages aren't a usable solution. In this version, I've made it INFO when verbose is set and DEBUG1 otherwise -- which aligns somewhat with some of the other messages in vacuumlazy.c - Melanie
v13-0001-Eagerly-scan-all-visible-pages-to-amortize-aggre.patch
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